List of top Questions asked in CBSE Class X

The following distribution shows the daily pocket allowance of children of a locality. The mean pocket allowance is Rs 18. Find the missing frequency f.

Daily pocket11 - 1313 - 1515 - 1717 - 1919 - 2121 - 2323 - 25
Number of workers76913f54

A survey was conducted by a group of students as a part of their environment awareness programme, in which they collected the following data regarding the number of plants in 20 houses in a locality. Find the mean number of plants per house. 

Number of plants  0 − 22 − 4 4 − 66 − 8 8 − 1010 − 1212 − 14
Number of houses

1

2

1

5

6

2

3

Which method did you use for finding the mean, and why?

An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric mains supply. What current is drawn from the line if the supply voltage is 220 V?
Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?
Explain why the planets do not twinkle?
Why do stars twinkle?
What happens to the image distance in the eye when we increase the distance of an object from the eye?
A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective lens used to restore proper vision?
How is the equal genetic contribution of male and female parents ensured in the progeny?
Outline a project which aims to find the dominant coat colour in dogs.
A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?
A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as
What could be the reasons for adopting contraceptive methods?

Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.

How does reproduction help in providing stability to populations of species?
A person needs a lens of power −5.5 diopters for correcting his distant vision. For correcting his near vision, he needs a lens of power +1.5 diopter. What is the focal length of the lens required for correcting?
(i) distant vision, and
(ii) near vision?
How are the modes for reproduction different in unicellular and multicellular organisms?
What are the different methods of contraception?
Why does menstruation occur?
What are the functions performed by the testes in human beings?
The change in focal length of an eye lens is caused by the action of the
What are the advantages of sexual reproduction over asexual reproduction?
The anther contains